Yes, the X-Men and the Fantastic Four are both in Avengers: Doomsday: Marvel announced the Fox-era X-Men cast and the Fantastic Four cast, and the trailer shows both teams. What Marvel has not done is explain how the three groups of heroes come together. This guide separates what is confirmed from what is guesswork. The film opens in US theaters on December 18, 2026 and in the UK on December 16, and the complete cast table is in our Avengers: Doomsday release date and cast guide.
Who is confirmed from the X-Men side
Marvel Studios revealed the cast on March 26, 2025, in a livestream of director’s chairs bearing actors’ names, which TheWrap covered. The X-Men names TheWrap lists are:
- Patrick Stewart as Charles Xavier
- Ian McKellen as Magneto
- James Marsden as Scott Summers/Cyclops
- Rebecca Romijn as Mystique
- Kelsey Grammer as Hank McCoy/Beast
- Alan Cumming as Kurt Wagner/Nightcrawler
- Channing Tatum as Gambit
Most of these actors played the same characters in the Fox X-Men films. Good Morning America’s report on the film names Stewart as Professor X, McKellen as Magneto and Marsden as Cyclops, which matches TheWrap.
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Who is confirmed from the Fantastic Four side
The Fantastic Four’s cast from The Fantastic Four: First Steps (2025) is also on the list: Pedro Pascal as Reed Richards/Mister Fantastic, Vanessa Kirby as Sue Storm, Joseph Quinn as Johnny Storm/Human Torch and Ebon Moss-Bachrach as Ben Grimm/The Thing. Good Morning America confirms Pascal and Quinn in its report.
What Marvel says about how they connect
Marvel’s official synopsis, as quoted by Good Morning America, reads: “Beloved heroes from three distinct universes will be set on a deadly collision course.” Those three universes appear to be the main MCU, the Fantastic Four’s reality and the X-Men’s world, but that is the outlet’s reading of the line, and Marvel has not published a longer plot summary. TheWrap’s cast report from March 2025 does not describe the story connection at all.
What the trailer shows
The July 20 trailer is the best evidence. Gizmodo and Kotaku both describe the X-Mansion as damaged and later blown up, with Stewart’s Professor X watching a strange light in the sky. Gizmodo adds that Xavier and Magneto clasp hands, and that Yelena Belova fights Mystique, who takes her form. Gambit fights Shang-Chi in all three trailer breakdowns we opened, including Screen Rant, which also mentions a brief shot of Cyclops. On the Fantastic Four side, Gizmodo says Thor brings the team into Avengers Tower, and M’Baku shakes hands with Ben Grimm.
Screen Rant reports screens behind the heroes showing three worlds at risk of colliding and Sentinel wreckage in the background of a battlefield. Whether those Sentinels belong to the X-Men’s world is Screen Rant’s guess, not something Marvel has said.
A connection that already exists in the MCU
Screen Rant’s watch-before list points out one earlier crossing: in The Marvels (2023), Monica Rambeau ends up in another universe inside the X-Mansion with Kelsey Grammer’s Beast. The same list suggests X-Men: Days of Future Past’s timeline rewrite “could” connect to the X-Men’s return, which is the writer’s theory. TV Insider reports that Robert Downey Jr.’s Doctor Doom first appeared in a brief post-credits scene in The Fantastic Four: First Steps, so the Fantastic Four’s film already linked to this one.
What is not confirmed
- Whether the X-Men are heroes, villains or both. The trailer shows them fighting other heroes, and no official source explains why.
- Which universe each group belongs to. Marvel has said “three distinct universes,” not named them.
- Anyone not on Marvel’s lists. We only treat a name as confirmed when Marvel or a named outlet backs it. The cast guide keeps reported and unconfirmed names in separate columns.
For the full release dates and more, return to the main Doomsday guide.
Sources
- TheWrap: Avengers: Doomsday cast livestream
- Good Morning America: trailer, release date and details
- Gizmodo: Avengers: Doomsday trailer breakdown
- Kotaku: Things we noticed in the first trailer
- Screen Rant: trailer breakdown
- Screen Rant: what to watch before Doomsday
- TV Insider via Yahoo: Doctor Doom comics and backstory guide
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